Persist web UI translation settings

tests/test_web_app.py

@@ -4,7 +4,8 @@ from __future__ import annotations
 
 import sys
 
-from web_app import build_pipeline_command, create_app
+import web_app
+from web_app import build_pipeline_command, create_app, load_translation_settings, save_translation_settings
 
 
 def test_build_pipeline_command_uses_cli_parser_defaults():
@@ -42,3 +43,37 @@ def test_create_app_builds_gradio_blocks():
     app = create_app()
 
     assert app.title == "Gradio YouTube Auto Dub"
+
+
+def test_save_and_load_translation_settings(tmp_path, monkeypatch):
+    settings_file = tmp_path / "web_settings.json"
+    monkeypatch.setattr(web_app, "SETTINGS_FILE", settings_file)
+
+    base_url, api_key, model, message = save_translation_settings(
+        "http://openai-compatible.local:8080/v1",
+        "secret-key",
+        "custom-model",
+    )
+
+    assert base_url == "http://openai-compatible.local:8080/v1"
+    assert api_key == "secret-key"
+    assert model == "custom-model"
+    assert str(settings_file) in message
+    assert load_translation_settings() == {
+        "base_url": "http://openai-compatible.local:8080/v1",
+        "api_key": "secret-key",
+        "model": "custom-model",
+    }
+
+
+def test_load_translation_settings_uses_env_defaults(tmp_path, monkeypatch):
+    monkeypatch.setattr(web_app, "SETTINGS_FILE", tmp_path / "missing.json")
+    monkeypatch.setenv("LM_STUDIO_BASE_URL", "http://env-host:1234/v1")
+    monkeypatch.setenv("LM_STUDIO_API_KEY", "env-key")
+    monkeypatch.setenv("LM_STUDIO_MODEL", "env-model")
+
+    assert load_translation_settings() == {
+        "base_url": "http://env-host:1234/v1",
+        "api_key": "env-key",
+        "model": "env-model",
+    }